There are 2 ways to go about this :
1. Measure the current collar of your dog :
- If it is a buckle collar you start the measurement from after the trident and including the bucle itself . The example in the pic is 40.5 cm
- If it is an adjustable collar, then you measure including the buckle and up top the hole you use currently. In the example picture first hole is at 38.5 cm as an example.
* I would not recommend to only go on by these measurements. Safety and 100% accuracy comes from measuring the dogs head so the collar doesn't slip off.
2. Measure your dogs neck and head size:
- Measure the middle or upper part of your dogs neck
- Measure the head size at the most wide part